No, it’s not because the painters couldn’t paint or because they had never seen a baby before.
According to Matthew Averett, an art history professor at Creighton University, it’s because there was a pious notion that Jesus came out of the womb already bearing the fully formed likeness of adult Jesus. There was really no such thing in the medieval western world as non-religious art, and most of the babies you see are either direct depictions of baby Jesus or cherubic type beings modeled after Jesus. So the goal was not to depict what real human babies look like but rather to depict homunculi: “little men” whose disconcerting appearance matched some era's ideals.
In the ancient Greek influenced thinking of the time, to be perfect was to be changeless. So Jesus could not be the perfect God-man if his appearance were to change with age. And since questioning things is more-or-less a modern invention, people didn’t trouble themselves very much with little logical inconsistencies like the fact that his infant body would obviously have to change into that of an adult man as well as his face.
This is not just a piece of academic trivia. Knowing about such historical oddities is important for this reason: we must always remember that our pious orthodoxies change over time. They always have. Changeless, old man Jesus was the embodiment of perfection because someone at some time decided so. Contradictorily, in an era like ours, which is more concerned with the needs of the individual, one often hears sermons around Christmas time celebrating the idea that Christ would fully share our experience of being a defenseless baby. Why? Because our era has decided that feeling solidarity in our helplessness with the human Jesus is a more immediate existential need to us than preserving the "immutability" of the "God-man."
To ask which era got it right or wrong is to misunderstand how religious symbols function in our collective psyche and the flexibility that these symbols need to have in order to hold their value over time.
So it’s very possible that the thing your hyper-Catholic aunt would be most appalled at you for questioning in this day and age is a temporary concern if one takes the long view. That, in and of itself, doesn’t mean that you shouldn’t come back around and embrace it yourself. This piety or that emphasis might pop in and out of importance in a given age for any number of very good reasons. But it could also be an arbitrary fixation that we shouldn't wait another hundred years to unload. And if you’re hyper-Catholic aunt knew her Catholic history better, she would hold onto it with a looser grip. And she would know that questioning it doesn't make her a “bad Catholic.” It makes her a traditional catholic. Because the tradition is one of change.
Cheers and Peace,
Jared Witt (Twitter: @realjaredwitt) is a pastor in the ELCA and, along with Aaron Schmalzle, is a Founding Director of Castle Church Brewing Community and Castle Church Faith Community. Checkout this blog weekly for reflections and updates or subscribe to our newsletter so that you never miss a thing.